350 MAG: Wrench sparked while changing cap; won't start now.

[FastMarkA]

I was changing the cap/rotor on the STBD engine, and while removing one of the ECM bolts (which is right under the 50 AMP breaker), some sparks flew off the wrench and then they stopped. (Ignition keys were off but battery switches were not.)

I completed the cap/rotor replacement, but when I went to start the engine, I got a bunch of errors on the Vessel View (low voltage, non-critical steering error, stbd start sequence), and the engine wouldn't even try to turn over. I didn't even hear a "click."

The 50 AMP breaker was not reset by the sparks (it seems); for good measure, I tested it and locked it back in, but still nothing.

The VesselView is displaying STBD engine data, so that makes me think some kind of power is getting to it for the ECM to be reporting such data. (When the STBD key is off and port is on, the pressure/temp/voltage display as hyphens.)

It's as if there is another fuse somewhere (possibly that 90 AMP on the slave solenoid?), or more likely, the silly VesselView needs its codes reset by the Merc software and everything will be fine.

Any obvious ideas before I go calling a the mechanic?

 

[paulswagelock]

When my breaker tripped, I received those same errors. Are you certain the breaker reset?

 

[FastMarkA]

When my breaker tripped, I received those same errors. Are you certain the breaker reset?

I pushed the red button and then jammed that yellow "flag" up a few times until it clicked...I wonder if the breaker is bad?

 

[SeaAyeOwe]

I really hope this is not the case for you - but I can tell you from prior experience that the ECM's or PCM's on these engines are really sensitive to stray current. Worse case would be that the ECM has a fried an ECM component. Not sure how hard it is on your configuration or how comfortable you are on this but on mine a swap of the bad ECM to the other engine would be a check before I called a mechanic.
If you do this, make sure you use a grounding strap from you to the engine ground when swapping just to make sure that you do not cause more damage with static.

 

[FastMarkA]

I really hope this is not the case for you - but I can tell you from prior experience that the ECM's or PCM's on these engines are really sensitive to stray current. Worse case would be that the ECM has a fried an ECM component. Not sure how hard it is on your configuration or how comfortable you are on this but on mine a swap of the bad ECM to the other engine would be a check before I called a mechanic.
If you do this, make sure you use a grounding strap from you to the engine ground when swapping just to make sure that you do not cause more damage with static.

Sage advice. I may give that a shot.

As a general comment, which could be completely unfounded since I'm not a mechanic by trade (but very comfortable with DIY), I'm pretty amazed at how many (what appear to be chintzy) wires that are running all over a very hot engine with lots of moving parts. It's like MerCruiser is begging for failure, but then again with a dealer network and profitable spare parts, that's precisely what they're doing.

 

[SeaAyeOwe]

Sage advice. I may give that a shot.

As a general comment, which could be completely unfounded since I'm not a mechanic by trade (but very comfortable with DIY), I'm pretty amazed at how many (what appear to be chintzy) wires that are running all over a very hot engine with lots of moving parts. It's like MerCruiser is begging for failure, but then again with a dealer network and profitable spare parts, that's precisely what they're doing.

Yes unfortunately - taking an on road engine design and fitting it into a bilge where you do not have the convenience of the vehicle chassis and body panels to run harnesses results in this spaghetti strapped to engine components - amplified by the additional number of sensors to monitor ancillaries because it is marine.

I have owned many boats though - and I personally think Searay do a better job than most if not all others on cable marking, drawings and some protection on the cabling.

 

[paulswagelock]

I pushed the red button and then jammed that yellow "flag" up a few times until it clicked...I wonder if the breaker is bad?

You can put a multimeter across it and test for continuity.

 

[Bt Doctur]

your getting power because your twin is wired as a single most likely. Also the alt feed and system power are combined on the 90A link at the starter. Check for 12v at the alt feed and the 50A breaker.
No reading=blown 90A link.
When you replace the 90A block, cut the system`s red wire off the block, extend it 6 inches, and connect it directly to the starter lug.

 

[FastMarkA]

All good tips here.

The best one yet as evidenced in the photo: yanking the engine out of the stupid bilge so I can walk around it and access everything without needing an Advil I.V.

 

[Bt Doctur]

that actually is the port motor removed for starter replacement from hydro-lock and a cracked head.
Everyone I find with that wiring arrangement I change.
No physical access to the starter without pulling the motor

 

[FastMarkA]

So it turns out the 90A fuse was the culprit. What a colossal b*tch to access it!

 

[Bt Doctur]

And the lesson learned is to remove the battery cable to prevent this from happening again when working around wires.
The reason to change the setup is because if the 90A fuse does blow while the motor is running
the alt will run wild and fry everything because its not hooked to the battery.
Stupid mercruiser design by a stupid engineer.

 

[FastMarkA]

And the lesson learned is to remove the battery cable to prevent this from happening again when working around wires.
The reason to change the setup is because if the 90A fuse does blow while the motor is running
the alt will run wild and fry everything because its not hooked to the battery.
Stupid mercruiser design by a stupid engineer.

You're so right! Very good advice.

 

[numlaar]

Definitely! Anytime working with electrical. Could have been a lot worse!